The Chinatown International District building that was the site of Washington state’s deadliest-ever massacre erupted in flames late Tuesday afternoon, wreaking havoc on the neighborhood but apparently not harming anybody.

More than 500 homes and businesses lost power and at least 22 people in surrounding buildings were forced to find another place to spend Christmas Eve because of the blaze, which spewed smoke late into the night.

Officials said they didn’t know what caused the fire on the abandoned top floor at 665 South King Street — site of the 1983 Wah Mee massacre.

Firefighters spent hours unsuccessfully trying to contain the blaze from outside the building, unable to enter because of concerns the 104-year-old structure could collapse.

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Now mostly vacant, the building is on a city “dangerous” list because it poses a high risk of fire and collapse.

“We’ll be here for a long time,” Seattle Fire Chief Gregory Dean said around 6 p.m., adding that the Fire Department had moved its trucks away from the building so they wouldn’t be in the “collapse zone.”

Authorities said Tuesday’s fire was unrelated to the building’s history. But for locals, its past added creepiness to the stunning blaze on a cool Christmas Eve.

“That building’s haunted,” said Joaquin Uy, a social-services advocate who lives on Beacon Hill but spends a lot of time in the Chinatown International District.

In the early morning hours of Feb. 19, 1983, three men entered the illegal Wah Mee gambling club in the building’s basement and hogtied, robbed and shot 14 people. Thirteen of them died; one survived and was able to identify the assailants.

Today, the building’s first floor is home to several popular businesses, including the Mon Hei Bakery, Palace Decor & Gifts and the Chinese Chamber of Commerce. But the two top floors have been vacant.

That’s where the two-alarm fire started just after 4 p.m., said Seattle Fire Department spokesman Kyle Moore.

Dozens of firetrucks arrived to help pump water into the building from above and from the side as hundreds of onlookers — some of whom had been evacuated from surrounding buildings — gathered to watch.

Smoke grayed the skies, water soaked the streets and, as the sun set, the area took on an almost-carnival atmosphere as onlookers gasped at the sheer size of the fire and the response.

“I hate to be a morbid spectator here, but those flames!” exclaimed Kerry Anderson, 66, a Seattle engineer who estimated he saw flames shooting 30 feet above the building.

Anderson and other local residents worried about water damage to businesses from the massive firefighting operation. Officials acknowledged that was a possibility.

“The bottom floor is basically an aquarium right now,” a Seattle police officer said.

The American Red Cross was called to help the evacuated residents, who officials hope can return to their homes on Christmas Day.

The crowd thinned as the night grew colder, but firefighting continued.

Moore said firefighters would keep putting water on the building all night but would not try to enter.

Material from The Times archives was included in this report.

Brian M. Rosenthal: 206-464-3195 or On Twitter @brianmrosenthal